Thermostatic circuit-closer.



A. M. DE 8. GREAVES.

THERMOSTATIC CIRCUIT CLOSER.

APPLICATION FILED MAY19.1917.

1,291,842 Patented Jan. 21, 1919.

.AIBILIO MARIA. DE SILVA GREAVES, OF GAMBRIDGE, MASSACHUSETTS;

TEERMOSTATIC CIRCUIT-CLOSER.

Specification of Letters Patent.

Patented J an. 21, 1919.

Application filed May 19, 1917. Serial No. 169,660.

To all whom it may concern:

Be it known that I, ABrLIo MARIA on SILVA GREAvns, a citizen of Portugal, residing at Cambridge, in the county of Middlesex and State of Massachusetts, have invented certain new and useful Improvements in Thermostatic Circuit Closers, of which the following is a specification, reference being 'hadtherein to the accompanying drawing.

This invention relates to improvements in thermoelectric fire alarm systems, and particularly to a novel construction of thermostatic circuit closer, for use in connection with such alarm systems.

The object of the invention is to provide a circuit closer which is simple, reliable and enficient in construction, which permits of the free expansion of the mercury beyond the point at which the circuit closing ac-' tion is efiected at the desired temperature, thus insuring a positive connection of the circuit terminals .by the mercury to close the circuit, and which embodies a construction particularly adapted to secure economy of manufacture.

With these and other objects in view, the invention consists of the features of construction, combination and arrangement of parts, hereinafter fully described and claimed, reference being hadto the accompanying drawing, in which Figure 1 is a view, partly diagrammatic,

illustrating my invention electrically con-.

nected up with an alarm device.

Fig. 2 is a vertical sectional view the circuit closer.

Fig. 3 is a similar view showing the seethrough tions of the device disconnected and arranged in proper relative position.

Figs. 4: and 5 are detail horizontal transverse sections on the lines 4-4 and 55 of Fig. 2.

Referring now more particularly to the drawing, an alarm system is shown including a mercury circuit closer, indicated as a whole at 1, and having terminals 2 and 3 connected with conductors 4 and 5, respectively, of an alarm circuit. Conductor i is connected with one pole or a source of current, indicated at 6, and the other pole of said source of current is connected by a conductor 7 with an alarm device which may be in the form of an electric bell 8. The connection of the conductor 7 with the alarm device 8 is indicated at 9, and conductor 5 is bore 14 through the opening 19 In view of. the fact that the device of my invention relates to the circuit closer, the latter is shown only in one figure connected up with the circuit, as the application to the circuit of other forms of my invention will be clearly understood by those skilled in the art.

Referring particularly to Fig. 2, which shows the general construction of the circuit closer, 11 designates a suitable base upon which the mercury tube 12 may be secured by means, such as a clip 13. The tube 12 is provided with a reduced bore 14 which terminates at its lower end in a bulb 15 and which is of suiilcient length to provide for considerable expansion of the mercury in the above points of normal temperature. The tube 12 will be preferably of glass, .and above the elevations of normal temperature to which the mercury may rise, said tube 12 is provided with an enlargement 16 which converges, as indicated at 1?, toward the normal cross section of the bore 14.

The enlargement 16 provides an expansion chamber for the expansion of the mercury therein, to reduce the rapidity of its ascent from the time that the expanding mercury reaches the divergingwall portions 17 of the expansion chamber, for a purpose which will presently appear. The thermostatic tube as a whole comprises two sections, a main or body section A and a top or head section B, the body section A having the features of construction above described. The upper end portion 18 of the body section extends above the expansion chamber in the form of a head of any suitable form in plan or cross section and having a -downwardly converging or tapering opening 19 extend ing from its upper face 20 downwardly into the top of the expansion chamber.

The top or head section B of the thermostatic tube is, like the main section A, preferably formed of glass or other insulating material, and is provided with a base or shoulder 2?. conforming in contour to the face 20 of. the head 18 and which is formed to snugly fit the same. From this or shoulder 21 depends a conical or tapering shank 22, which extends downward centrally into the expansion chamber 16 and has its apex or pointed lower and terminating in line with the bore connected with the alarm device as indicated base portion- 14 and in close proximity tothe converging portions of the inner wall of the expansion chamber leading thereto, the upper portion of the shank serving as a stopper or closer for the opening 19.

Above the base or shoulder 21 the section B is provided with a pair of parallel members or fork arms 23, which are of circular or other suitable form in cross section, and which are provided with downwardly extending bores or passages 24 leading from theirupper ends to and through the base or shoulder 21, adjacent diametrically opposite sides of the shank or tapered extension 22, and partially circular grooves 25 extending along said shank to the tip or apex thereof in alinement with the bores 2%, Metallic cap pieces 26 and 27 are fitted upon the fork arms 23 and provided with binding posts 28 and 29 carrying clamping nuts 30 and 31 for the attachment of conductors thereto, the said binding posts and clamping nuts form ing the terminals 2 and 3 to which the conduo-tors d and 5 of the alarm circuit are connected.

Conducting wires 32 and 33 extend through the bores 24 of the fork arms and are electrically connected at their upper ends with the binding posts, and the lower portions of these wires are fitted and secured in the grooves of the shank or extension 22, as by the use of cement, and have their free ends projecting slightly beyond the tip or apex of the shank or extension 22 in the form of contact terminals 34 and 35, which terminals are disposed in alinement with the mercury bore 14.- and in spaced relation there to and to each other, said contact terminals being however in sufiiciently close proximity to be electrically connected by the mercury immediately upon the expansion of the mercury from the upper end of the bore 14 into the base of the expansion chamber. The cap section B is secured to the body section A. by cementing or otherwise securing the faces 20 and 21 together and also cementing the shank or extension 22 within the conical or tapered passage 21.

It will be understood from the foregoing description that the contacts 34' and 35 are arranged just above the normal thermostatic point to which the mercury is allowed to expend before sounding the alarm, and that when the mercury expands beyond such point into theexpansion chamber the contact terminals 34 and 35, which are electrically connected with the conductors a and 5, will energize the circuit and sound the alarm. it will be observed that the shank or extension 22 terms a partition sub-dividing the expansion chamber into separate compartinents into which portions of the mercury may expand, and that by reason of the lobular form of the chamber and tapering orm of the shank the compartments of the expansion chamber first radually increase in size and then diminish in size upwardly, whereby the mercury is permitted to expand to a suitable degree beyond the normal without divided portions of the mercury will be in contact with the wires throughout the exposed portions of the latter. Hence even in the event of imperfect conductivity of a portion of either wire, another portion thereof will be in contact with the mercury, thus positively connecting the terminals to energize the alarm circuit.

Another important advantage of my in vention is that by constructin the thermostatic tube in sections, as escribed, the tube is adapted to be molded or otherwise economically made, and by providing seat grooves for the wires, the necessity o? boring, dressing or otherwise finishing the surfaces of the parts is obviated or reduced to a material extent, with resultant production.

of a high low cost.

Having described my invention, I claim: 1. A. thermostatic circuit closer including a mercury tube comprising horizontally di vided cap sections, said sections having grade article at a comparatively united abutment faces, thebody section being provided with a mercury bulb at its lower end, an expansion chamber at its upper end having a flaring opening leading downwardly thereinto from the abutment face of the body section, and a mercury bore connecting the mercury bulb with the lower end of the expansion chamber, and the said bores and a tapered-depending extension closing the said flaring opening and secured therein and extending downwardly into the expansion chamber, said tapered extension being provided with diametrically opposite grooves leading from the bores of the up right members to the tip of'said extension conducting wires extending through said cap having upright members provided with its lower end, an expansion chamber at its cap section having upright members provided with bores and a tapered depending extension closing the said flaring opening and cemented therein and extendin downwardly into the expansion chamber, said tapered extension being provided with diametrically opposite rooves leading from the bores of the uprig t members to the tip of said extension, conducting wires extending through said bores of the upright members and seat and cemented in the grooves of the tapered extension, said wires having their lower ends projecting beyond the apex of said extension and forming contacting terminals, and binding posts mounted upon the upright members and electrically connected with the conducting wires.

In testimony whereof I hereunto aifix my signature in the presence of two witnesses.

ABILIO imam 1m SILVA GREAVES.

Witnesses: AUoUs'ro J. TAVEIRA, ARTHUR J. Tavern. 

